Multi-stream access scheme for high speed access and recording using a hard disk drive

ABSTRACT

A system for high-speed access and recording includes a demodulator, a buffer memory, and a hard disk. During a write cycle, a content stream is stored in buffer memory and thereafter transferred to the demodulator. When the buffer memory reaches its storage capacity, its contents are transferred to the hard disk for storage. During a read cycle, contents from the hard disk are read and then stored in the buffer memory. The hard disk further includes includes a high-speed zone and a random-access zone, which are configured to operate in a high-speed mode, a random-access mode, and a buffer-cleaning mode.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application claims the benefit of priority under 35 U.S.C. §119 from U.S. Provisional Patent Application Ser. No. 60/333,695,entitled “MULTI-STREAM ACCESS SCHEME FOR HIGH-SPEED RECORDING USING AHARD DISK DRIVE” filed on Nov. 26, 2001, and U.S. Provisional PatentApplication Ser. No. 60/333,963, entitled “MULTI-STREAM ACCESS SCHEMEFOR HIGH-SPEED RECORDING USING A HARD DISK DRIVE” filed on Nov. 27,2001, the disclosures of which are hereby incorporated by reference inits entirety for all purposes.

BACKGROUND OF THE INVENTION

The present invention relates generally to storage systems, and moreparticularly to method and circuitry for implementing multi-streamhigh-speed data access and recording in a storage system.

FIG. 1 is a simplified schematic diagram of a conventional hard disk. Acontroller 102 moves a disk head 104 across the surface of a hard disk106. The hard disk 106 is divided into annular tracks 108. Each track108 is divided into contiguous sectors 110. Each track 108 can hold alarge number of sectors 110. In a conventional construction, one sector110 typically holds five hundred and twelve (512) bytes of data. Harddisks holding twenty (20) or more Gbits are common. Different types ofdata or content program information can be stored on a hard diskincluding, for example, audio, video, data, etc. A content program, suchas a movie of DVD quality, is generally made up of one or more files.Each file is further broken into byte groups. Each byte group is storedin a sector.

FIG. 2 is a simplified schematic diagram showing memory allocation of aconventional hard disk file system. During write cycles, sectors 110 arerandomly accessed depending on which sectors are available. Availablesectors are randomly located around the hard disk. Sectors 110 of FIG. 2are further characterized as available blocks 112 and filled blocks 114.As shown in FIG. 2, the available blocks 112 and the filled blocks 114are not necessarily stored in a contiguous manner, i.e., some filledblocks 114 may be situated between available blocks 112 and vice versa.

Conventional random allocation of sectors is typically preferred becausesuch allocation enables a hard disk to be used to its full capacity.During a write cycle, each byte group is placed into an available ortarget sector. The available sector can come from any location on thehard disk. Sectors from any part of the hard disk can become available,and thereafter are subject to being rewritten. Before a byte group isplaced into the target sector, the disk head (not shown) must firstidentify and then move to the target sector. While the positioning ofthe disk head over the target sector might require long head movements,this approach utilizes the hard disk to its fullest capacity. Once thedisk head is positioned over the target sector, the actual writing ofthe byte group to that target sector can be very fast, e.g., greaterthan fifty (50) MB/sec. The time it takes for the disk head to positionover the target sector, however, can take a relatively substantialamount of time, e.g., 10-40 msec. This is because the available sectorsfor writing are randomly located on the hard disk. Consequently, theavailable sectors need to be initially identified or searched which addsto the access time in both write and read cycles.

Due to the need to search for the available sectors, access times mayvary depending on how far the disk head must travel across the harddisk. For example, if the disk head must travel from one sector toanother and both sectors are in relatively close proximity, the accesstime might be relatively fast, e.g., 10 ms. If, however, the disk headis originally positioned towards the outer edge of the hard disk andmust then travel towards the center of the hard disk, then the accesstime can be relatively slow, e.g., 40 ms. Thus, the range of accesstimes may also vary depending on the size of the hard disk, and willlikely increase with larger hard disks.

Furthermore, excessively long access time may cause loss of data whenread and write cycles are alternated. Due to multi-tasking, aconventional system almost always has to alternate between read andwrite cycles. Alternating between read and write cycles can occur in anumber of different situations including, for example, when a user whois recording and viewing a content program, such as a movie, stopsviewing the movie temporarily and returns to viewing from where the userleft off. Recording of the movie, however, continues despite thetemporary viewing stoppage. In this situation, since there is only onedisk head in the system, the disk head has to be moved aroundalternately to retrieve the next block of data for display to the userand then search for the next available sectors for storing data on thehard disk. If the access time for the read cycle becomes intolerablylong, then the resulting disruption in the viewing of the movie maybecome noticeable to the user. Likewise, if the access time for thewrite cycle is too slow, information can be lost because the disk headmay stop writing in order to initiate the next read cycle to read datathat is needed for display to the user.

A number of statistical models have been used to measure the averagefallout of conventional systems, i.e., the amount of information lost.The average fallout increases when multiple streams of information arereceived. For example, two tuners might be employed to receive twoinformation streams from two different sources. In this situation, thedisk head may be limited by its own speed and may not be able to handlewrite cycles in a sufficiently fast manner to allow both informationstreams to be recorded.

Hence, it would be desirable to provide a storage system that is able tohandle multi-stream data access and recording in a more efficient mannerso as to improve system performance and minimize loss of data.

BRIEF SUMMARY OF THE INVENTION

A system for facilitating high-speed access and recording is provided.In one exemplary embodiment, the system includes a demodulator, a buffermemory and a hard disk. During a write cycle, the demodulator is used toreceive one or more content streams. The content streams received by thedemodulator are first stored in the buffer memory. When the buffermemory has reached its storage capacity, its contents are thentransferred to the hard disk for storage. During a read cycle, contentsfrom the hard disk are read and then stored in the buffer memory. Othercomponents of the system can then access the read-out contents from thebuffer memory. The amount of contents retrieved from the hard disk andstored in the buffer memory may be more than what is requested dependingon the application requesting the contents.

In one exemplary embodiment, the buffer memory is made up of a number ofservice units. Two service units are assigned to each content stream,one for the read operation and the other for the write operation. Eachservice unit further includes a pair of sub-units. For the writeoperation, the sub-units are alternately filled with the content streamand emptied onto the hard disk.

In one exemplary embodiment, the hard disk further includes differentzones. There are two types of zones, namely, high-speed zone andrandom-access zone. The two different types of zones allow for a numberof operating modes, namely, the high-speed mode, the random-access modeand the buffer-cleaning mode. In the high-speed mode, contents from thebuffer memory are transferred to the high-speed zone in a continuousmanner regardless of the nature or classification of the contents. Inthe random-access mode, contents from the buffer memory are respectivelytransferred to the appropriate locations in the random-access zone basedon the nature or classification of the contents. In the buffer-cleaningmode, contents stored in the high-speed zone are transferred toappropriate locations in the random-access zone based on the nature orclassification of the contents.

Reference to the remaining portions of the specification, including thedrawings and claims, will realize other features and advantages of thepresent invention. Further features and advantages of the presentinvention, as well as the structure and operation of various embodimentsof the present invention, are described in detail below with respect toaccompanying drawings, like reference numbers indicate identical orfunctionally similar elements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified schematic diagram of a conventional hard disk;

FIG. 2 is a simplified schematic diagram illustrating memory allocationof a conventional hard disk file system;

FIG. 3 is a simplified block diagram of a multi-stream access systemaccording to one exemplary embodiment of the present invention;

FIG. 4 is a simplified schematic diagram of a buffer memory according toone exemplary embodiment of the present invention;

FIG. 5 is a simplified schematic diagram of a hard disk according to oneexemplary embodiment of the present invention;

FIG. 6 is a simplified schematic diagram illustrating detailed memoryallocation of a hard disk according to one exemplary embodiment of thepresent invention; and

FIG. 7 is a simplified schematic diagram illustrating detailed memoryallocation of a hard disk according to another exemplary embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention in the form of one or more exemplary embodimentswill now be described. FIG. 3 is a simplified block diagram of amulti-stream access and recording system 130 according to one exemplaryembodiment of the present invention. In an exemplary embodiment, themulti-stream access and recording system 130 includes a number ofdemodulators 132, a buffer memory 134, a microprocessor 136 and a harddisk 138. The hard disk 138 can be a standard hard disk that is readilyavailable commercially. It should be understood that the hard disk 138is described herein for illustrative purposes only and that a person ofordinary skill in the art will know how to apply the present inventionother types of storage media. The hard disk 138 further includes aninternal memory 140, a controller 142 and a number of storage elements146. The hard disk 138 and the microprocessor 136 are connected via ahigh speed data bus 144. The demodulators 132 are used to respectivelyreceive data or contents from multiple content streams. Each incomingcontent stream can have a different data rate. The number of contentstreams coming into the demodulators 132 may vary depending on thespecific design and/or application. Data or contents from the contentstreams received by the demodulators 132 are then input and stored inthe buffer memory 134.

The demodulators 132 can be implemented in a number of ways. In oneexemplary implementation, a single demodulator is used to receive onecontent stream or channel. In an alternative exemplary implementation, asingle demodulator is able to handle multiple content streams orchannels. An example of a multi-channel demodulator is described inco-owned and co-pending non-provisional U.S. patent application Ser. No.09/956,479, filed on Sep. 18, 2001, entitled “A Digital Implementationof Multi-Channel Demodulators,” which is hereby incorporated byreference for all purposes.

Furthermore, it should be noted that in alternative embodiments, othertypes of data receivers can be used in place of the demodulators 132. Aperson of ordinary skill in the art will know how to use other types ofdata receivers in the present invention.

The buffer memory 134 functions as a data buffer zone for high-speeddata access and recording. As will be further described below, thebuffer memory 134 is capable of receiving data from both thedemodulators 132 and the storage medium 138, depending on whichoperating mode is active. The buffer memory 134 can be either internalor external to the hard disk 138. The buffer memory 134 can be any of anumber of commonly available storage media. The capacity of the buffermemory 134 may vary depending on the specific design and/or application.Based on the disclosure and teachings provided herein, a person ofordinary skill in the art will appreciate how to implement the buffermemory 134 and determine its capacity.

In one exemplary embodiment, the multi-stream access and recordingsystem 130 can operate in two operating modes, namely, a write mode anda read mode. During the write mode, the buffer memory 134 first receivesfrom the demodulators 132 data or contents corresponding to one or morecontent streams. It should be understood that, for ease of description,the content streams are meant to include their corresponding data orcontents. The content streams are initially stored in the buffer memory134 until certain predetermined conditions are met. Such conditionsinclude, for example, the buffer memory 134 reaching a predeterminedcapacity threshold and a temporary holding period expiring. When thepredetermined conditions are met, the microprocessor 136 sends thecontents of the buffer memory 134 across the high-speed bus 142 to thehard disk 138, more specifically, the internal memory 140 associatedwith the hard disk 138. The controller 142 then directs the internalmemory 140 to forward its contents to the storage elements 146 withinthe hard disk 138 for storage purposes. By storing the content streamsinto the buffer memory 134 first, a larger amount data is written to thehard disk 138 each time the disk head (not shown) of the hard disk 138is positioned to record. Consequently, movement relating to the diskhead of the hard disk 138 is reduced.

During the read mode, data is retrieved from the hard disk 138 pursuantto an access request and the data is then stored in the buffer memory134. The amount of data to be retrieved and stored in the buffer memory134 varies depending on the application utilizing the data. A predictivealgorithm or method can be used to determine how much data is to beretrieved and stored in the buffer memory 134. The amount of dataretrieved is more than the amount requested by the access request. Theadditional data is retrieved in anticipation of a subsequent accessrequest. Data stored in the buffer memory 134 can then be accessed orread by other components of the system. For example, if the datarepresents a movie and the movie is being viewed by a user, a certainamount of data can be retrieved and stored in the buffer memory 134ahead of time before such data is needed for viewing; in anotherexample, if the user fast-forwards a movie, additional data is retrievedand stored in the buffer memory 134 in anticipation of subsequent accessrequests to be issued in connection with the fast-forward function. Theamount of data to be retrieved and stored in the buffer memory 134depends on the specific design and/or application. By storing data intothe buffer memory 134 before it is needed, a larger amount of data isretrieved from the hard disk 138 each time the disk head of the harddisk 138 is positioned to read from the hard disk 138 and movementrelating to the disk head of the hard disk 138 is also reduced.

FIG. 4 is a simplified schematic diagram of one exemplary embodiment ofthe buffer memory 134. In this exemplary embodiment, the buffer memory134 is divided into a number of service units 152(1 . . . n). It shouldbe noted that “n” is an arbitrary number that is selected based on aspecific design and/or application. Preferably, the size of the serviceunits 152(1 . . . n) are roughly the same. In other embodiments, thesize of each service unit 152 may vary depending on the specific designand/or application.

In one exemplary embodiment, two service units are allocated for eachcontent stream, one for use in the write mode and one for use in theread mode. With two service units, continuous and concurrent read andwrite operations can be performed on the content stream. In otherembodiments, one service unit can be assigned to one content stream;alternatively, more than two service units can be allocated to onecontent stream. When multiple service units are assigned to one contentstream, the service units are used in a sequential order to receive thecontent stream. For example, the service units are filled one afteranother with data from the content stream. The number of service unitsassigned to each content stream may vary depending on the specificdesign and/or application.

In one exemplary embodiment, each service unit is further partitionedinto two sub-units designated “A” and “B” with a pair of sub-units beingreferred to as a “ping-pong buffer unit”. For example, service unit152(1) is divided into sub-units 152(1A) and 152(1B) Within eachping-pong buffer unit, either sub-unit A or sub-unit B is filled firstto a predetermined capacity threshold and then followed by the other.

During the write mode, sub-unit A, for example, is filled with a contentstream first. Once sub-unit A is filled up to its predetermined capacitythreshold, the content stream is directed to flow into sub-unit B. Whilesub-unit B is being filled, the contents in sub-unit A are sent to thehard disk 138 for storage, as described above. When sub-unit B is filledup to its predetermined capacity threshold, the content stream isredirected to flow into the now available sub-unit A and contents insub-unit B is transferred and stored onto the hard disk 138. Sub-units Aand B are filled and their contents transferred onto the hard disk 138in this alternating manner. The transfer rates from sub-units A and B tothe hard disk 138 need not be, but they preferably are, the same and therates are sufficiently fast such that data can continuously streamthrough the ping-pong buffer. In other embodiments, each service unit152 could be divided into more than two sub-units. For example, onealternative embodiment can include sub-units A, B, and C. Similarly, themultiple sub-units A, B and C are sequentially filled to theirrespective predetermined capacity threshold and the contents of eachsub-unit are stored onto the hard disk 138 once that sub-unit is filled.

FIG. 5 is a simplified schematic diagram of one exemplary embodiment ofa hard disk 150 designed for high-speed multiple-stream access andrecording according to the present invention. In this specificembodiment, the hard disk 150 is partitioned into different zones. Eachzone can be used in both write and read modes. Furthermore, at least onezone is dedicated to “high-speed” recording, as will be furtherdescribed below.

In an exemplary embodiment, the hard disk 150 includes one or morehigh-speed zones 160(1 . . . n) and one or more random-access zones162(1 . . . n). It should be noted that “n” is an arbitrary numberselected based on a specific design and/or application. It should alsobe noted that the number of high-speed zones 160 and the number ofrandom-access zones 162 do not necessarily have to be the same. Theexact number of zones and the specific function of each zone may varydepending on the specific design and/or application. In someembodiments, each zone can serve a special function. For example, onerandom-access zone 162(1) can be dedicated for storing large videofiles; and another random-access zone 162(2) can be dedicated for smalldata files. The precise size, location, and function of each zone mayvary depending on the specific design and/or application. Each zone ispartitioned into a number of zone units (not shown), and each zone unitis partitioned into sectors. The actual sizes of the zone units andtheir configurations may vary depending on the specific design and/orapplication. In some embodiments, a zone can be further divided intosub-zones. For example, a random-access zone 162 can be divided intospecialized sub-zones for storing video data, audio data and other typesof data respectively.

The hard disk 138 with its different zones allows for a number ofoperating modes. In an exemplary embodiment, the operating modes includea high-speed mode, a random-access mode and a buffer-cleaning mode.Based on the disclosure and teachings provided herein, it should beunderstood that other types of operating modes can be implementeddepending on the zones available in the associated storage medium.

In the high-speed mode, two types of operations, namely, write and readcycles, can be performed. The write and read cycles are asynchronous andare independent of each other. In the write cycle, content streams beingrecorded onto the hard disk 138 are initially stored in the high-speedzone 160 regardless of the type of data contained within the contentstreams. As noted above, the content streams are transferred from thebuffer memory 134. Content streams are recorded to the high-speed zone160 continuously. That is, zone units within the high-speed zone 160 arefilled sequentially one after another. The size of each zone unit ispreferably (although not necessarily) fixed and the exact size of eachzone unit depends on the specific design and/or application. In someembodiments, the zone unit being filled is contiguous to the previouslyfilled zone unit. While consecutively filled zone units need not becontiguous, the recording rate is improved if such zone units arecontiguous because no search is required to locate the next availablezone units. If a read cycle is introduced while recording, the positionof the last or most recently filled zone unit is recorded. When the readcycle is completed, the subsequent write cycle can then swiftly locatethe recorded position to continue where it left off without a search.

By storing the content streams in the high-speed zone 160 in thismanner, the access time for a read cycle is reduced. Each read cyclerequires only one search to locate the sector containing the initialposition of the target data. Once the initial position is located, dueto the close proximity of the zone units, the access time is decreasedwhen the target data is read from the high-speed zone 160.

The use of the high-speed zone 160 as described above offers a number ofadvantages and/or benefits. For example, the use of the high-speed zone160 is particularly advantageous when there is asymmetric access.Asymmetric access refers to a situation in which there is substantiallymore data recording onto the hard disk 138 than data retrieval from thehard disk 138, such as, where a user uses a personal video recording(PVR) system to download and record large video files for subsequentviewing. With the high-speed zone 160, the video files are stored inclose proximity to one another thereby allowing more efficientsubsequent access. In addition, the use of the high-speed zone 160allows a system to improve its throughput capacity by storing data ontoa storage medium more swiftly.

In an exemplary embodiment, the content streams are stored in thehigh-speed zone 160 on a temporary basis. After a predetermined periodof time or when certain conditions are met, contents from the high-speedzone 160 are transferred to the random-access zone 162. The contenttransfer from the high-speed zone 160 to the random-access zone 162 willbe further described below.

In the random-access mode, content streams are stored directly onto therandom-access zones 162(1 . . . n). Similarly, content streams aretransferred from buffer memory 134 directly to the random-access zones162(1 . . . n). The random-access zones 162(1 . . . n) can be organizedin a number of different ways based on various criteria. For example,the random-access zones 162(1 . . . n) can be organized based on thetype of data that such zones are supposed to contain, such as, videodata, audio data and text data. Furthermore, as mentioned above, arandom-access zone 162 can be further divided into specializedsub-zones. Such sub-zones can also be organized based on additionalcriteria. Based on the disclosure and teachings provided herein, aperson of ordinary skill in the art will know of the various differentways and/or methods to organize the random-access zones in accordancewith the present invention.

When content streams are processed in the random-access mode, they arestored onto respective random-access zones 162(1 . . . n) or sub-zones.For example, data from a movie can be stored in a random-access zonethat is classified for storing video files and further in a sub-zoneunder that random-access zone that is classified for storing video filesfor movies. The random-access mode is engaged typically when accesscapacity of a system is sufficiently met to allow content streams to bestored in more specific locations on the hard disk 138. Also, asmentioned above, contents from the high-speed zone 160 can betransferred into the random-access zones 162. Such transfer is effectedunder the buffer-cleaning mode, as will be further described below.

In the buffer-cleaning mode, the hard disk 138 is defragmented toprovide access and recording optimization. In effect, the system“cleans” the data or contents from the high-speed zone 160. Morespecifically, data is transferred from the high-speed zone 160 to therandom-access zone 162 for future read cycles. The transfer can betriggered manually or on an automated basis after a specified timeperiod has expired or when certain conditions are met. For example, insome embodiments, the buffer-cleaning mode is engaged when no contentstreams are being recorded. As described above, the random-access zone162 can be organized based on different criteria and can be furtherdivided into specialized sub-zones. Consequently, in the buffer-cleaningmode, content streams from the high-speed zone 160 are first examinedaccordingly based on the criteria used in organizing the random-accesszones 162 and their corresponding sub-zones, if any, and then dependingon the results of the examination the content streams are respectivelytransferred to the appropriate locations in the random-access zones 162.In addition, in the buffer-cleaning mode, a number of maintenanceservices are performed on the contents of the random-access zones 162.For example, contents of a random-access zone 162 can be defragmented toprovide better content organization, access optimization and spaceutilization. Organizing and storing data into random-access zones 162reduces access times for future read cycles. Accordingly, as hard drivesincrease in size, access times can be minimized.

FIG. 6 is a simplified schematic diagram illustrating detailed memoryallocation of a hard disk according to one exemplary embodiment of thepresent invention. There is shown a representative portion of the harddisk 150 which includes high-speed zones 160(1 . . . n) andrandom-access zones 162(1 . . . n). The hard disk 150 is made up ofmemory blocks 165. More specifically, memory blocks representing thehigh-speed zones 160 are grouped together in a contiguous manner; andmemory blocks representing the random-access zones 162 are also groupedtogether in a contiguous manner but separated from the memory blocksrepresenting the high-speed zones 160.

FIG. 7 is a simplified schematic diagram illustrating detail memoryallocation of a hard disk according to another exemplary embodiment ofthe present invention. There is shown a representative portion of thehard disk 150 which includes a number of storage units. In someembodiments, hard disk 150 has three different types of storage units:superrecording units 170(1 . . . n), recording block units 165(1 . . .n), and basic units (not demarcated). One or more super-recording units170 are used to implement the high-speed zones 160. Each super-recordingunit 170(1 . . . n) can include one or more recording block units 165(1... n). Preferably, all the recording block units in a super-recordingunit 170 are physically located close to or contiguous with each other.Each recording block unit 165 includes many basic units. For example,one recording block unit 165 can contain two hundred and fifty-six (256)basic units. Each basic unit can vary in size, e.g., five hundred andtwelve (512) bytes, the size of a conventional sector in a hard disk.

It can be seen that the present invention in the form of one or moreexemplary embodiments as described above provide a number of advantagesand/or benefits. Principally, the present invention allows high-speedaccess and recording of multiple content streams of data. The presentinvention can be deployed in a number of applications. For example, thepresent invention can be used in a personal video recording system toprovide better system performance. A person of ordinary skill in the artwill appreciate how to deploy or use the present invention in othercontexts and/or applications.

It is understood that the examples and embodiments described herein arefor illustrative purposes only and that various modifications or changesin light thereof will be suggested to persons skilled in the art and areto be included within the spirit and purview of this application andscope of the appended claims. All publications, patents, and patentapplications cited herein are hereby incorporated by reference for allpurposes in their entirety.

1. A system for facilitating high-speed access and recording of multiplecontent streams, comprising: a buffer memory configured to storerespective contents from one or more content streams, wherein thecontents include at least one video program of finite temporal length;and a hard disk configured to store the respective contents from the oneor more content streams stored in the buffer memory and including ahigh-speed zone and a random-access zone, wherein: in a high-speed mode,the contents stored in the buffer memory are transferred to thehigh-speed zone wherein zone units of the high-speed zone are filledsequentially, in a random access mode, the contents stored in the buffermemory are transferred to the random-access zone, in a buffer-cleaningmode, the contents stored in the high-speed zone are transferred to therandom-access zone if a predetermined period of time has elapsed, andthe contents stored in the buffer memory are transferred to the harddisk for storage if a capacity threshold of the buffer memory isreached.
 2. The system of claim 1 wherein contents from the hard diskare loaded into the buffer memory pursuant to an access requestrequesting contents; wherein the contents loaded into the buffer memoryinclude the contents requested by the access request and additionalcontents related to the contents requested by the access request; andwherein the additional contents are loaded into the buffer memory inanticipation of a subsequent access request.
 3. The system of claim 2wherein the subsequent access request is satisfied by the additionalcontents stored in the buffer memory thereby reducing access to the harddisk.
 4. The system of claim 1 wherein the buffer memory furthercomprises a plurality of service units; wherein at least one contentstream is associated with a first service group having one or moreservice units and the at least one content stream is associated with theone or more service units; and wherein in a write operation, the one ormore service units within the first service group are filled in a firstsequential order with contents from the at least one content stream, andcontents from the filled one or more service units are transferred tothe hard disk in the first sequential order.
 5. The system of claim 4wherein at least one of the plurality of service units includes aplurality of sub-units; and wherein in the write operation, theplurality of sub-units are filled in a second sequential order with thecontents from the associated content stream, and contents from thefilled sub-units are transferred to the hard disk in the secondsequential order.
 6. The system of claim 4 wherein at least one contentstream is associated with a second service group having one or moreservice units; and wherein in a read operation, the one or more serviceunits within the second service group are filled in a second sequentialorder with contents from the hard disk.
 7. The system of claim 1 whereinin the high-speed mode, the contents transferred to the high-speed zoneare stored in close proximity to each other or in a contiguous manner.8. The system of claim 1 wherein the random-access zone includes aplurality of sub-zones, each sub-zone configured to store contentsmatching a specified criterion; and wherein in the random access mode,the contents transferred from the buffer memory to the random-accesszone are examined and respectively forwarded to the correspondingsub-zones for storage based on the specified criteria of the pluralityof sub-zones.
 9. The system of claim 8 wherein in the buffer-cleaningmode, the contents transferred from the high-speed zone to therandom-access zone are examined and respectively forwarded to thecorresponding sub-zones for storage based on the specified criteria ofthe plurality of sub-zones.
 10. A personal video recording systemincorporating the system as recited in claim
 1. 11. A system forfacilitating high-speed access and recording of multiple contentstreams, comprising: a storage medium configured to receive and storerespective contents from one or more content streams, the storage mediumhaving a plurality of zones including a high-speed zone and arandom-access zone, and the contents including at least one videoprogram of finite temporal length; wherein in a high-speed mode, therespective contents from the one or more content streams are directed tothe high-speed zone for storage and zone units of the high-speed zoneare filled sequentially; wherein in a random-access mode, the respectivecontents from the one or more content streams are directed to therandom-access zone for storage; and wherein in a buffer-cleaning mode,the contents stored in the high-speed zone are transferred to therandom-access zone if a predetermined period of time has elapsed. 12.The system of claim 11 wherein in the high-speed mode, the respectivecontents from the one or more content streams are stored in closeproximity to each other or in a contiguous manner in the high-speedzone.
 13. The system of claim 11 wherein the random-access zone includesa plurality of sub-zones, each sub-zone configured to store contentsmatching a specified criterion; and wherein in the random access mode,the respective contents from the one or more content streams areexamined and respectively forwarded to the corresponding sub-zones forstorage based on the specified criteria of the plurality of sub-zones.14. The system of claim 13 wherein in the buffer-cleaning mode, thecontents transferred from the high-speed zone to the random-access zoneare examined and respectively forwarded to the corresponding sub-zonesfor storage based on the specified criteria of the plurality ofsub-zones.
 15. The system of claim 11 wherein the storage medium is ahard disk.
 16. A personal video recording system incorporating thesystem as recited in claim
 11. 17. The system of claim 11 furthercomprising: a buffer memory configured to store the respective contentsfrom the one or more content streams; wherein the contents stored in thebuffer memory are transferred to the storage medium for storage when apredetermined condition is met.
 18. The system of claim 17 wherein thepredetermined condition includes a situation where capacity threshold ofthe buffer memory is reached.
 19. The system of claim 17 whereincontents from the storage medium are loaded into the buffer memorypursuant to an access request requesting contents; wherein the contentsloaded into the buffer memory include the contents requested by theaccess request and additional contents related to the contents requestedby the access request; and wherein the additional contents are loadedinto the buffer memory in anticipation of a subsequent access request.20. The system of claim 19 wherein the subsequent access request issatisfied by the additional contents stored in the buffer memory therebyreducing access to the storage medium.
 21. The system of claim 17wherein the buffer memory further comprises a plurality of serviceunits; wherein at least one content stream is associated with a firstservice group having one or more service units and the at least onecontent stream is associated with the one or more service units; whereinin a write operation, the one or more service units within the firstservice group are filled in a first sequential order with contents fromthe at least one content stream, and contents from the filled one ormore service units are transferred to the storage medium in the firstsequential order.
 22. The system of claim 21 wherein at least one of theplurality of service units includes a plurality of sub-units; andwherein in the write operation, the plurality of sub-units are filled ina second sequential order with the contents from the associated contentstream, and contents from the filled sub-units are transferred to thestorage medium in the second sequential order.
 23. The system of claim21 wherein at least one content stream is associated with a secondservice group having one or more service units; and wherein in a readoperation, the one or more service units within the second service groupare filled in a second sequential order with contents from the storagemedium.
 24. A method for facilitating high-speed access and recording ofmultiple content streams, comprising: storing respective contents fromone or more content streams in a buffer memory, wherein the contentsinclude at least one video program of finite temporal length;transferring the respective contents from the one or more contentstreams to a hard disk when a capacity threshold of the buffer memory isreached; configuring the hard disk to include a high-speed zone and arandom-access zone; transferring the contents stored in the buffermemory to the high-speed zone if the hard drive is in a high-speed mode,wherein zone units of the high-speed zone are filled sequentially;transferring the contents stored in the buffer memory to therandom-access zone if the hard disk is in a random access mode; andtransferring the contents stored in the high-speed zone to therandom-access zone if the hard disk is in a buffer-cleaning mode and ifa predetermined period of time has elapsed.
 25. The method of claim 24further comprising: loading contents from the hard disk into the buffermemory pursuant to an access request requesting contents; wherein thecontents loaded into the buffer memory include the contents requested bythe access request and additional contents related to the contentsrequested by the access request; and wherein the additional contents areloaded into the buffer memory in anticipation of a subsequent accessrequest.
 26. The method of claim 25 further comprising: satisfying thesubsequent access request using the additional contents loaded into thebuffer memory thereby reducing access to the hard disk.
 27. The methodof claim 24 wherein the buffer memory further comprises a plurality ofservice units and the method further comprises: assigning a firstservice group having one or more service units to at least one contentstream, wherein the at least one content stream is associated with thefirst service group and the one or more service units; and when in awrite operation, filling the one or more service units within the firstservice group in a first sequential order with contents from the atleast one content stream, and transferring contents of the filled one ormore service units to the hard disk in the first sequential order. 28.The method of claim 27 wherein at least one of the plurality of serviceunits includes a plurality of sub-units and the method furthercomprises: when in the write operation, filling the plurality ofsub-units in a second sequential order with the contents from thecorresponding content stream, and transferring contents from the filledsub-units to the hard disk in the second sequential order.
 29. Themethod of claim 27 further comprising: assigning a second service grouphaving-one or more service units to at least one content stream; andwhen in a read operation, filling the one or one service units withinthe second service group in a second sequential order with contents fromthe hard disk.
 30. The method of claim 24 wherein in the high-speedmode, the contents transferred to the high-speed zone are stored inclose proximity to each other or in a contiguous manner.
 31. The methodof claim 24 further comprising: dividing the random-access zone into aplurality of sub-zones, each sub-zone configured to store contentsmatching a specified criterion; when in the random access mode,forwarding the contents transferred from the buffer memory to therandom-access zone respectively to the corresponding sub-zones forstorage based on the specified criteria of the plurality of sub-zones.32. The method of claim 31 further comprising: when in thebuffer-cleaning mode, forwarding the contents transferred from thehigh-speed zone to the random-access zone respectively to thecorresponding sub-zones for storage based on the specified criteria ofthe plurality of sub-zones.
 33. A personal video recording systemutilizing the method as recited in claim
 24. 34. A method forfacilitating high-speed access and recording of multiple contentstreams, comprising: dividing a storage medium into a plurality of zonesincluding a high-speed zone and a random-access zone; storing respectivecontents from one or more content streams in a buffer memory, whereinthe contents include at least one video program of finite temporallength; when in a high-speed mode, storing the respective contents fromthe one or more content streams that are in the buffer memory in thehigh-speed zone, wherein zone units of the high-speed zone are filledsequentially; when in a random-access mode, storing the respectivecontents from the one or more content streams that are in the buffermemory in the random-access zone; and when in a buffer-cleaning mode, ifa select predetermined period of time has elapsed, transferring thecontents stored in the high-speed zone to the random-access zone. 35.The method of claim 34 wherein in the high-speed mode, the respectivecontents from the one or more content streams are stored in closeproximity to each other or in a contiguous manner in the high-speedzone.
 36. The method of claim 34 further comprising: dividing therandom-access zone into a plurality of sub-zones, each sub-zoneconfigured to store contents matching a specified criterion; when in therandom access mode, forwarding the respective contents from the one ormore content streams respectively to the corresponding sub-zones forstorage based on the specified criteria of the plurality of sub-zones.37. The method of claim 36 further comprising: when in thebuffer-cleaning mode, forwarding the contents transferred from thehigh-speed zone to the random-access zone respectively to thecorresponding sub-zones for storage based on the specified criteria ofthe plurality of sub-zones.
 38. The method of claim 34 wherein thestorage medium is a hard disk.
 39. A personal video recording systemutilizing the method as recited in claim
 36. 40. The method of claim 34further comprising: storing the respective contents from the one or morecontent streams in an buffer memory; and transferring the contentsstored in the buffer memory to the storage medium when a predeterminedcondition is met.
 41. The method of claim 40 wherein the predeterminedcondition includes a situation where a capacity threshold of the buffermemory is reached.
 42. The method of claim 40 further comprising:loading contents from the storage medium into the buffer memory pursuantto an access request requesting contents; wherein the contents loadedinto the buffer memory include the contents requested by the accessrequest and additional contents related to the contents requested by theaccess request; and wherein the additional contents are loaded into thebuffer memory in anticipation of a subsequent access request.
 43. Themethod of claim 42 further comprising: satisfying the subsequent accessrequest using the additional contents stored in the buffer memorythereby reducing access to the storage medium.
 44. The method of claim40 wherein the buffer memory further comprises a plurality of serviceunits and the method further comprises: assigning a first service grouphaving one or more service units to at least one content stream, whereinthe at least one content stream is associated with the first servicegroup and the one or more service units; when in a write operation,filling the one or more service units within the first service group ina first sequential order with contents from the at least one contentstream, and transferring contents from the filled one or more serviceunits to the storage medium in the first sequential order.
 45. Themethod of claim 44 wherein at least one of the plurality of serviceunits includes a plurality of sub-units and the method furthercomprises: when in the write operation, filling the plurality ofsub-units in a second sequential order with the contents from theassociated content stream, and transferring contents from the filledsub-units to the storage medium in the second sequential order.
 46. Themethod of claim 44 further comprising: assigning a second service grouphaving one or more service units to at least one content stream; andwhen in a read operation, filling the one or more service units withinthe second service group in a second sequential order with contents fromthe storage medium.